Evaluating medical tests and biomarkers In primary studies and systematic reviews

This thesis addresses methodological problems in the evaluation of tests and biomarkers, in quite distinct types of research. The first part addresses systematic reviews and meta-analysis of diagnostic accuracy: discrimination between diseased and non-diseased (cross-sectional design; dichotomous test use). The second part presents primary studies of prognostic factors and clinical prediction rules: the probability of developing an event (continuous test result) in studies that include a time element. Both parts focus on discrimination between patient groups and the best ways to assess and express the discriminating ability of a test or model.